Sound isolating (SI) earphones and headsets are becoming increasingly popular for music listening and voice communication. SI earphones enable the user to hear and experience an incoming audio content signal (be it speech from a phone call or music audio from a music player) clearly in loud ambient noise environments, by attenuating the level of ambient sound in the user ear-canal.
The disadvantage of such SI earphones/headsets is that the user is acoustically detached from their local sound environment, and communication with people in their immediate environment is therefore impaired. If a second individual in the SI earphone user's ambient environment wishes to talk with the SI earphone wearer, the second individual must often shout loudly in close proximity to the SI earphone wearer, or otherwise attract the attention of said SI earphone wearer e.g. by being in visual range. Such a process can be time-consuming, dangerous or difficult in critical situations. A need therefore exists for a “hands-free” mode of operation to enable an SI earphone wearer to detect when a second individual in their environment wishes to communicate with them.
WO2007085307 describes a system for directing ambient sound through an earphone via non-electronic means via a channel, and using a switch to select whether the channel is open or closed.
Application US 2011/0206217 A1 describes a system to electronically direct ambient sound to a loudspeaker in an earphone, and to disable this ambient sound pass-through during a phone call.
US 2008/0260180 A1 describes an earphone with an ear-canal microphone and ambient sound microphone to detect user voice activity.
U.S. Pat. No. 7,672,845 B2 describes a method and system to monitor speech and detect keywords or phrases in the speech, such as for example, monitored calls in a call center or speakers/presenters using teleprompters.
But the above art does not describe a method to automatically pass-through ambient sound to an SI earphone wearer when a key word is spoken to the SI earphone wearer.